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I02 INFECTIOUS LEUKAEMIA 



puscles and increase in the number of white ones, as deter- 

 mined by blood counts made daily or every other day, from 

 the time of inoculation or of feeding the virus until the daj' of 

 death. 



The diminution in the number of red corpuscles and the in- 

 crease in the number of white ones are illustrated in the blood 

 count of two cases of artificialh' produced disease, (p. 105). 

 In carefull)' heated cover-glass preparations of healthy 

 fowl blood stained with methylene-blue and eosin, the nuclei 

 are colored a deep blue, and the cellular protoplasm surround- 

 ing the nucleus is stained by the eosin. In similar prepara- 

 tions made from the blood of the affected fowls there are a 



J ,-^,^„.„ greater or less number of 



corpuscles which do not 

 take the eosin stain. In 

 these the portion of the 

 corpuscle surrounding the 

 nucleus remains unstained 

 or becomes slightly tinted 

 with blue. It occasionally 

 contains one or more vacu- 

 oles, and the margin is fre- 

 quently broken. In some in- 

 stances a considerable por- 

 tion of the corpuscle has 

 disappeared, leaving a few 

 free nuclei. The apparent 

 dissolving away of the red 

 corpuscles has been fre- 

 quently observed, and cor- 

 puscles showing the inter- 

 mediate stages are readily detected in carefully prepared 

 specimens. 



The cau.se of the destruction of the red corpuscles is not 

 yet satisfactorily explained. In his report on fowl cholera, 

 Salmon illustrates leucocytes surrounding the red corpuscles, 

 but the marked diminution of the red cells was not deter- 

 mined. He speaks, however, of the pale color of the blood. In 



% 



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Fig. 16. Blood from a ivell ad- 

 vanced case of infectious leiikacmia 

 shoiuing changes in red corpuscles and 

 increase in nuviher of leucocytes. 



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